Although we've heard plenty of speeches in the past couple of years from Obama administration officials acknowledging that the United States uses armed drones to bomb suspected terrorists overseas, we've received precious little actual information about who the government is killing, where and why.

Tuesday's hearing should begin to change that.

At least some members of Congress are clearly fed up with the administration's excessive secrecy about who the American government is killing and where exactly we're at war -- as they should be. Rand Paul mounted a 13 hour filibuster to demand more information about the drone program, and got a couple of memos that raise as many questions as they answered.

The unanswered questions extend far beyond Paul's primary focus on how the U.S. justifies killing American citizens. Of the thousands killed by U.S. drones, we only know of four that have been Americans. What is the U.S. government's basis for killing some 4700 other people?

Despite officials' speeches, we still don't really know. CIA Director John Brennan, for example, has claimed the United States targets only senior al Qaeda leaders, as part of the United States' global war against al Qaeda. But as a recent McClatchy investigation revealed, based on a review of classified documents, only a tiny percentage -- fewer than two percent -- have actually been al Qaeda leaders. The rest have been lower level "insurgents," "fighters" or "militants," as the U.S. government calls them, although it's never defined that term. Moreover, they were not all linked to al Qaeda. In many cases, it's not clear whom those individuals were fighting for -- or against.

Of course, some targeted killing is lawful in a war, when it's clear the targets are members of enemy armed forces or civilians directly participating in hostilities. But to be legally considered an armed conflict, the level of fighting must be far more intense than merely sporadic acts of terrorism. And it must be clear who our enemy actually is.

Outside an actual armed conflict, it's only lawful to kill someone who poses an imminent threat to human life. (This is similar to the situation in law enforcement, when police can shoot to kill, say, an armed suspect holding hostages.)

It's not at all clear the United States has followed those well-established international rules. That's led some foreign governments to refuse to cooperate with U.S. counterterrorism efforts. Meanwhile, popular sentiment in places like Pakistan and Yemen, where our government is bombing, has grown increasingly anti-American.

The result is a more dangerous environment in exactly the places where we're most concerned about terrorism, and a less robust intelligence network available to address it.

The first problem for Congress to tackle on Tuesday is the U.S. government's excessive secrecy about its drone war.

We know the U.S. isn't targeting only al Qaeda leaders; so who is it targeting? And is it following the laws governing self-defense in the face of an imminent threat, or the laws of war, which allow a much broader use of lethal force? If it's operating under the laws of war, where is the U.S. in an armed conflict? In Yemen and Pakistan? What about Somalia? Both Congress and the American people deserve to know where our government is fighting a war and how we are choosing targets.

The Congressional committee should also ask how many civilians the United States has killed in this so-called "targeted killing" program. Estimates from independent organizations suggest about 20 -- 25 percent of the dead have been civilians. The government refutes that, but needs to provide actual data and explain what it's doing to prevent civilian deaths and to compensate the families and communities that are harmed when they occur.

Then there's the question of whether it even makes sense to rely so heavily on targeted killing as a counterterrorism strategy.

Former government officials such as CIA chief Robert Grenier, Director of National Intelligence Dennis Blair and Gen. Stanley McChrystal have all warned that the drone program is creating enemies overseas and must be used more sparingly. Congress should explore that as well.

This should be the first of many hearings on a subject that has troubled both allies and potential enemies around the world. If we are going to fight terrorism with drones, then we also need to share the reasons for our actions with allies and with the local populations our actions affect. Only by revealing the real facts of the U.S. drone war will the United States be able to marshal the support it needs -- and to curb the potential blowback.